Temporary implantable medical electrical stimulation lead

ABSTRACT

A temporary implantable medical device lead includes a connector configured to connect the lead to an external control module. A helically coiled conductor includes a proximal end that is mechanically and electrically connected to the connector. The conductor includes a plurality of insulated filars. An insulative layer is removed from an uninsulated portion of each of the filars near a distal end of the conductor. The uninsulated portion of each of the filars is exposed at an outer surface of the conductor such that the exposed uninsulated portions of the filars define a plurality of electrodes at longitudinally spaced sections near the distal end of the conductor.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No. 61/675,407, filed Jul. 25, 2012, which is herein incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to implantable medical leads. More particularly, the present disclosure relates to temporary implantable medical leads including a plurality of electrodes.

BACKGROUND

Temporary implantable medical leads may be used to evaluate the efficacy of stimulation (e.g., neurostimulation) prior to implanting chronically implantable systems within a patient. For example, as a treatment for urinary incontinence, patients may be implanted with a trial percutaneous nerve evaluation (PNE) lead to evaluate the efficacy of sacral nerve stimulation.

Temporary leads that incorporate only one electrode (i.e., unipolar) are used in conjunction with a ground pad. The ground pad is applied to the patient's skin and connected to the electrical stimulation element to complete the electrical circuit. The ground pad may cause the patient discomfort, and can become dislodged or disconnected during the test period, thus preventing test stimulation therapy from occurring. In addition, the temporary lead may migrate, potentially causing the unipolar lead to lose the ability to deliver effective therapy. As a result, higher non-responder rates can occur in patients receiving the temporary lead compared to patients receiving a permanent pacing lead to evaluate the efficacy of stimulation.

SUMMARY

Disclosed herein are various embodiments of a temporary implantable medical device lead including multiple stimulation electrodes, as well as medical device systems including such temporary implantable medical device leads.

In Example 1, a temporary implantable medical device lead includes a connector configured to connect the lead to an external control module. A helically coiled conductor has a proximal end mechanically and electrically connected to the connector. The conductor includes a plurality of insulated filars. An insulative layer is removed from an uninsulated portion of each of the filars near a distal end of the conductor. The uninsulated portion of each of the filars is exposed at an outer surface of the conductor such that the exposed uninsulated portions of the filars define a plurality of electrodes at longitudinally spaced sections near the distal end of the conductor.

In Example 2, the temporary implantable medical device lead according to Example 1, wherein a first electrode is defined by the uninsulated portion of at least one of the plurality of filars and a second electrode is defined by the uninsulated portions of at least one other of the plurality of filars.

In Example 3, the temporary implantable medical device lead according to either Example 1 or Example 2, and further comprising a conductive mechanical element including one or more grooves that electrically couple with the uninsulated portion of at least one filar.

In Example 4, the temporary implantable medical device lead according to Example 3, wherein one or more grooves have a depth approximately equal to a diameter of the retained at least one filar.

In Example 5, the temporary implantable medical device lead according to any of Examples 1-4, and further comprising one or more conductive elements wound co-radially with and electrically coupled to the uninsulated portion of at least one filar of the conductor, wherein the one or more conductive elements are not mechanically connected to the connector at the proximal end.

In Example 6, the temporary implantable medical device lead according to Example 5, wherein the one or more conductive elements comprises one or more additional filars.

In Example 7, the temporary implantable medical device lead according to Example 5, wherein the one or more conductive elements comprises a ribbon conductor.

In Example 8, the temporary implantable medical device lead according to any of Examples 1-7, wherein the plurality of filars are wound in alternating multi-turn segments, and wherein one or more multi-turn segments for each filar are exposed at the outer surface of the conductor to define the plurality of electrodes.

In Example 9, a system includes an externally carried control module and a temporary implantable medical device lead. The temporary implantable medical device lead includes a connector configured to connect the lead to the control module. A helically coiled conductor includes proximal end mechanically and electrically connected to the connector. The conductor includes a plurality of insulated filars. An insulative layer is removed from an uninsulated portion of each of the filars near a distal end of the conductor. The uninsulated portion of each of the filars is exposed at an outer surface of the conductor such that the exposed uninsulated portions of the filars define a plurality of electrodes at longitudinally spaced sections near the distal end of the conductor. During stimulation, the control module is configured to operate a first of the plurality of electrodes as a cathode and a second of the plurality of electrodes as an anode.

In Example 10, the system according to Example 9, wherein a first electrode is defined by the uninsulated portion of at least one of the plurality of filars and a second electrode is defined by the uninsulated portions of at least one other of the plurality of filars.

In Example 11, the system according to either Example 9 or Example 10, and further comprising a conductive mechanical element including one or more grooves that electrically couple with the uninsulated portion of at least one filar.

In Example 12, the system according to Example 11, wherein one or more grooves have a depth approximately equal to a diameter of the retained at least one filar.

In Example 13, the system according to any of Examples 9-12, and further comprising one or more conductive elements wound co-radially with and electrically coupled to the uninsulated portion of at least one filar of the conductor, wherein the one or more conductive elements are not mechanically connected to the connector at the proximal end.

In Example 14, the system according to Example 13, wherein the one or more conductive elements comprises one or more additional filars.

In Example 15, the system according to Example 13, wherein the one or more conductive elements comprises a ribbon conductor.

In Example 16, the system according to any of Examples 9-15, wherein the plurality of filars are wound in alternating multi-turn segments, and wherein one or more multi-turn segments for each filar are exposed at the outer surface of the conductor to define the plurality of electrodes.

In Example 17, a temporary implantable medical device lead includes a connector configured to connect the lead to an externally carried control module, and a lead body including a helically coiled conductor having a proximal end mechanically and electrically connected to the connector. The conductor includes a plurality of insulated filars. An insulative layer is removed from an uninsulated portion of each of the filars near a distal end of the conductor. The uninsulated portion of each of the filars is exposed at an outer surface of the lead body such that the exposed uninsulated portions of the filars define a plurality of electrodes at longitudinally spaced sections.

In Example 18, the temporary implantable medical device lead according to Example 17, wherein a first electrode is defined by the uninsulated portion of at least one of the plurality of filars and a second electrode is defined by the uninsulated portions of at least one other of the plurality of filars.

In Example 19, the temporary implantable medical device lead according to either Example 17 or Example 18, and further comprising a conductive mechanical element including one or more grooves that electrically couple with the uninsulated portion of at least one filar.

In Example 20, the temporary implantable medical device lead according to Example 19, wherein one or more grooves have a depth approximately equal to a diameter of the retained at least one filar.

While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a multipolar temporary lead positioned proximate the sacral nerves of a patient.

FIG. 2 is a cross-sectional view of an embodiment of a temporary lead coil conductor including a multifilar conductor having insulative coating removed to form a plurality of electrodes.

FIG. 3A is a side view of an embodiment of a temporary lead coil conductor including a mechanical element disposed within turns of the coil conductor to define an electrode.

FIG. 3B is a cross-sectional view of the temporary lead coil conductor illustrated in FIG. 3A.

FIG. 4 is a cross-sectional view of an embodiment of a temporary lead coil conductor including a contoured ribbon formed among turns of the coil conductor to define an electrode.

FIG. 5 is a cross-sectional view of an embodiment of a temporary lead coil conductor including one or more additional filars wound with turns of the coil conductor to define an electrode.

FIG. 6 is a cross-sectional view of an embodiment of a temporary lead coil conductor including a conductive ribbon wound with turns of the coil conductor to define an electrode.

FIG. 7 is a cross-sectional view of an embodiment of a temporary lead coil conductor including a plurality of filars wound in alternating multi-turn segments.

While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

FIG. 1 illustrates an embodiment of an electrical stimulation system 10 including a control module (e.g., stimulator or pulse generator) 12 and a temporary implantable medical device lead 14 coupled to the control module 12. In some embodiments, the electrical stimulation system 10 is a peripheral nerve evaluation (PNE) stimulation system, which allows temporary implantation of a lead at a nerve site to test whether neurostimulation at the site improves the condition being treated. In the embodiment shown, the lead 14 is implanted proximate a sacral nerve N of a patient P. In other embodiments, the electrical stimulation system 10 is configured to provide stimulation to other nerve bundles or other portions or systems of the body. While illustrated and described as a temporary lead, the lead 14 may alternatively be configured as a chronically implanted lead.

The control module 12 is configured to deliver stimulation signals to the lead 14 and/or receive electrical signals sensed by the lead 14. In some embodiments, the control module 12 is an externally carried or worn device. The control module 12 may include external controls 15 that allow the clinician to set characteristics (e.g., periodicity, frequency, amplitude, etc.) of the therapy delivered to the sacral nerve N via the lead 14. The control module 12 may also include an antenna 16 configured to communicate with an external device (e.g., programmer), for example to receive programming related to therapy delivery.

The lead 14 includes a proximal end 17 and a distal end 18. In some embodiments, the distal end 18 of the lead 14 includes a plurality of electrodes (not shown) positioned proximate to the sacral nerve N. The lead 14 may be introduced from the posterior side of the sacrum, through a foramen thereof, and into the region of the sacral nerves and positioned such that a plurality of electrodes at the distal end 18 is in close vicinity to the sacral nerve N for electrical stimulation. At the percutaneous entry site on the back of the patient P, the lead 14 may be coiled and affixed to the skin with a transparent dressing 19. At the proximal end 17, the lead includes a connector 20 configured to mechanically and electrically couple the lead 14 to the control module 12. The connector 20 may include a plurality of contacts that electrically couple the electrodes at the distal end 18 of the lead 14 to the electrical components of the control module 12 via a conductor extending through the lead 14.

The conductor extending through the lead 14 is a helically coiled multifilar conductor. As used herein, a filar may be a single conductive wire or a cable comprising a plurality of bundled wires. The multifilar conductor is electrically connected to the control module 12 such that different wires of the conductor are capable of carrying different electrical signals for stimulation of the sacral nerve N. In some embodiments, the multifilar conductor is electrically insulated with a layer of insulating material that surrounds each filar. According to embodiments of the present disclosure, and as will be more fully described herein, the insulative layer is removed from an uninsulated portion of each of the filars near the distal end 18. The uninsulated portion of each of the filars is exposed at an exterior of the body of the lead 14 such that the exposed uninsulated portions of the filars define the plurality of electrodes at longitudinally spaced sections along a distal region near the distal end of the lead 14.

With a plurality of electrodes, the lead 14 according to the present disclosure is configured for multipolar stimulation, thereby eliminating the ground pad used in unipolar PNE systems. In addition, the multiple electrodes at the distal end 18 of the lead 14 improves the likelihood that therapeutic stimulation of the sacral nerve N is consistently delivered during the evaluation period, due to the number of electrodes disposed in proximity to the sacral nerve N. That is, even if the lead 14 migrates during the evaluation period and one of the electrodes at the distal end 18 moves away from the sacral nerve N, other electrodes at the distal end 18 may come into contact with the sacral nerve N after the migration.

In some embodiments, the lead 14 has a relatively small outer diameter D. In some embodiments, the outer diameter D is less than about 0.05 inch (1.27 mm). For example, in some embodiments, the outer diameter is less than about 0.025 inch (0.635 mm). The outer diameter D may be such that the lead 14 can be implanted using a small diameter needle having a lumen diameter corresponding to the outer diameter D. For example, in some embodiments, the needle used for implantation of the lead 14 may be a 16 gauge or 20 gauge foramen needle.

In some embodiments, the outer surface of the lead 14 is defined by the insulated and uninsulated filars of the lead conductor. In alternative embodiments, the lead 14 may include a lead body 24 that covers the lead conductor. Portions of the lead body 24 at the location of uninsulated portions of the lead conductor at the distal end 18 may be removed to expose the electrodes at an exterior of the lead body 24. In some embodiments, the lead body 24 is comprised of an insulative material, such as, for example, ethylene tetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), parylene, other fluoropolymers, silicone, polyurethane, polyester, or rubber. In alternative embodiments, the lead 14 does not include an insulative lead body 24.

FIG. 2 is a cross-sectional view of an embodiment of a multifilar temporary lead coil conductor 40 according to the present disclosure. The portion of the lead conductor 40 illustrated in FIG. 2 is near the distal end 18 of the lead 14, and does not illustrate the distal tip of the lead 14 or the portions of the lead proximal to the electrodes. In the embodiment shown, the conductor 40 includes four filars 42 a, 42 b, 42 c, and 42 d. While four filars 42 a-42 d are shown, any number of filars 42 is possible. For example, in other embodiments, the conductor 40 includes two to eight filars. The filars 42 a-42 d may be comprised of a conductive material such as, for example, stainless steel, MP35N, platinum, platinum-iridium, or tantalum.

The filars 42 a-42 d are wound co-radially with each other such that the filars 42 a-42 d define a helically wound coil including an inner lumen 43. In some embodiments, the inner lumen 43 has a diameter of less than about 0.015 inch (0.381 mm), and is configured to allow passage of a stylet for delivery of the lead 14 to the implantation site.

The filars 42 a-42 d are each coated circumferentially with an insulative material 44 a, 44 b, 44 c, and 44 d, respectively. The insulative material 44 a-44 d electrically isolates the filars 42 a-42 d from each other. In some embodiments, the insulative material 44 a-44 d is comprised of a material such as, for example, ETFE, PTFE, parylene, silicone, or polyurethane, although other insulative materials are also possible. In some embodiments, the insulative material 44 a-44 d on each of the filars 42 a-42 d is comprised of the same insulative material. In alternative embodiments, the insulative material 44 a-44 d differs between some of the filars 42 a-42 d.

The diameter of each of the filars 42 a-42 d may be less than about 0.006 inch (0.152 mm), and a thickness of the insulative material 44 a-44 d may be less than about 0.002 inch (0.051 mm). In some embodiments, the thickness of the insulative material 44 a-44 d is in the range of about 0.00025 inch to about 0.001 inch (0.006-0.025 mm). The filars 42 a-42 d are closely wound such that the spacing between adjacent turns of the conductor 40 is less than about 0.005 inch (0.127 mm). In some embodiments, the spacing between adjacent turns of the conductor 40 is less than about 0.001 inch (0.025 mm).

In various embodiments, the insulative layer 44 a-44 d is removed from sections of the filars 42 a-42 d near the distal end 18 of the lead 14 to define a plurality of longitudinally spaced electrodes. For example, the insulative layer 44 a-44 d may be removed from sections of the filars 42 a-42 d via an ablation process. In the embodiment shown, the insulative layer 44 a-44 c is removed from the filars 42 a-42 c, respectively, to expose the conductive material of the filars 42 a-42 c at an exterior of the lead 14. The uninsulated portions of the filars 42 a-42 c define an electrode 46. Also in the embodiment shown, the insulative layer 44 d is removed from the filar 42 d to expose the conductive material of the filar 42 d at an exterior of the lead 14 and define an electrode 48. The electrode 48 is located distally from the electrode 46. While electrodes 46, 48 are illustrated as extending co-radially with the insulated portions of the filars 42 a-42 d, in some embodiments, the electrodes 46, 48 are disposed at the outer surface of the conductor 40 to form a substantially constant outer diameter. That is, in some embodiments, the outer diameter of the insulated filars 42 a-42 d is approximately equal to the outer diameters of the electrodes 46, 48. In still further embodiments, the outer diameters of the electrodes 46 and/or 48 are greater than the outer diameter of the insulated filars 42 a-42 d.

In some embodiments, the filars 42 a-42 c terminate proximal to the electrode 48 such that turns of the filar 42 d are adjacent to each other at the electrode 48. Alternatively, the filars 42 a-42 c may extend distal to the electrode 48 in insulated form. While the electrode 46 is shown defined by three filars 42 a-42 c and the electrode 48 is shown defined by one filar 42 d, the electrodes 46 and 48 can alternatively be defined by any number of filars 42 in the conductor 40 (e.g., two filars define electrode 46 and two filars define electrode 48). In some embodiments, the turns of the uninsulated portions of the filars 42 a-42 c that define electrode 46 and/or the uninsulated portion of the filar 42 d that defines electrode 48 are welded together. In some embodiments, the longitudinal lengths of the electrodes 46, 48 are less than about 0.500 inch (12.7 mm). For example, the electrodes 46, 48 may be approximately 0.100 inch (2.54 mm) in length. In some embodiments, the electrodes 46, 48 are disposed on the distal one inch (25.4 mm) of the lead 14.

FIG. 3A is a side view, and FIG. 3B is a cross-sectional view, of a portion of a temporary lead coil conductor 50 according to another embodiment of the present disclosure. In the illustrated embodiment, the conductor 50 is a bifilar conductor including filars 52 a and 52 b coated by insulative layers 54 a and 54 b, respectively. The filars 52 a and 52 b may be comprised of a conductive material such as those discussed herein with respect to filars 42 a-42 d. The insulative layers 54 a and 54 b may be comprised of an insulative material such as those discussed herein with respect to insulative layers 44 a-44 d. In addition, the dimensions of the filars 52 a and 52 b and insulative layers 54 a and 54 b may be similar to the dimensions of filars 42 a-42 d and insulative layers 44 a-44 d as described herein. While the conductor 50 includes two filars 52 a and 52 b, the conductor 50 may alternatively include more than two filars.

The conductor 50 includes proximal mechanical element 56 and distal mechanical element 58. In some embodiments, the mechanical elements 56 and 58 are solid machined elements comprising a conductive material, such as, for example, stainless steel, MP35N, platinum, platinum-iridium, or tantalum, although other conductive materials are also possible. The mechanical elements 56 and 58 are configured to receive turns of the filars 52 a and 52 b and retain the filars 52 a and 52 b at an exterior of the lead 14. In some embodiments, the mechanical element 56 includes longitudinally spaced grooves 60 and the mechanical element 58 includes longitudinally spaced grooves 62 sized and shaped to receive turns of the filars 52 a and 52 b. FIG. 3A illustrates a side view of the portion of the conductor 50 including the proximal mechanical element 56.

In the embodiment shown, the insulative layer 54 a is removed (e.g., via ablation) from the filar 52 a along the portion of the filar 52 a retained by the proximal mechanical element 56, and the insulative layer 54 b is removed from the filar 52 b along the portion of the filar 52 b retained by the distal mechanical element 58. The uninsulated portion of the filar 52 a and the mechanical element 56 define a proximal electrode 64 and the uninsulated portion of the filar 52 b and the mechanical element 58 define a distal electrode 68. In some embodiments, the uninsulated portions of filars 52 a, 52 b are connected to the mechanical elements 56, 58 by, for example, laser welding in one or more locations or along the entire length of the mechanical elements 56, 58.

In some embodiments, the depths of the grooves 60, 62 in the mechanical elements 56, 58 are such that the grooves 60, 62 that retain the uninsulated portions of the filars 52 a, 52 b are not as deep as the grooves 60, 62 that retain the portions of the filars 52 a, 52 b including the insulative layers 54 a, 54 b. For example, the depth of the grooves 60, 62 that retain the uninsulated portions of the filar 52 a, 52 b may be approximately equal to the diameter of the uninsulated filars 52 a, 52 b, and the depth of the grooves 60, 62 that retain the insulated portions of the filar 52 a, 52 b may be approximately equal to the diameter of the insulated filars 52 a, 52 b. In this configuration, the exterior surface of the lead 14 remains substantially uniform, while positioning the uninsulated portions of the filars 52 a, 52 b at the exterior surface of the lead 14. In alternative embodiments, the electrodes 66, 68 have a greater outer diameter than the outer diameter of the insulated filars 52 a, 52 b.

The lead 14 may optionally include a tip cover 68 at a distal end 18. The tip cover 68 may be molded or bonded onto the distal end 18 and facilitates easy traversal of the lead 14 to the implantation site. Alternatively, the tip cover 68 is comprised of a conductive material such that the tip cover 68 is operable as a distal electrode.

FIG. 4 is a cross-sectional view of a temporary lead coil conductor 70 according to another embodiment of the present disclosure. In the illustrated embodiment, the conductor 70 is a bifilar conductor including filars 72 a and 72 b coated by insulative layers 74 a and 74 b, respectively. The filars 72 a and 72 b may be comprised of a conductive material such as those discussed herein with respect to filars 42 a-42 d. The insulative layers 74 a and 74 b may be comprised of an insulative material such as those discussed herein with respect to insulative layers 44 a-44 d. In addition, the dimensions of the filars 72 a and 72 b and insulative layers 74 a and 74 b may be similar to the dimensions of filars 42 a-42 d and insulative layers 44 a-44 d as described herein. While the conductor 70 includes two filars 72 a and 72 b, the conductor 70 may alternatively include more than two filars.

The conductor 70 is a variation on the conductor 50 illustrated in FIGS. 3A and 3B, wherein instead of solid elements defining the electrode structure, the electrode structure is defined by a mechanical element 76 comprising a contoured conductive ribbon structure. In this arrangement, the uninsulated portions of the filar defining the electrode (e.g., filar 72 a in FIG. 4) are retained in a groove 80 defined in the mechanical element 76, and the insulated filar (e.g., filar 72 b in FIG. 4) is alternatingly wound between turns of the mechanical element 76. The uninsulated portions of the filar 72 a and the electrically coupled mechanical element 76 define an electrode 84 on the lead 14. Similar mechanical elements may be formed at other longitudinally spaced sections of the lead 14 to define additional electrodes.

FIG. 5 is a cross-sectional view of a temporary lead coil conductor 90 according to another embodiment of the present disclosure. In the illustrated embodiment, the conductor 90 is a bifilar conductor including filars 92 a and 92 b coated by insulative layers 94 a and 94 b, respectively. The filars 92 a and 92 b may be comprised of a conductive material such as those discussed herein with respect to filars 42 a-42 d. The insulative layers 94 a and 94 b may be comprised of an insulative material such as those discussed herein with respect to insulative layers 44 a-44 d. In addition, the dimensions of the filars 92 a and 92 b and insulative layers 94 a and 94 b may be similar to the dimensions of filars 42 a-42 d and insulative layers 44 a-44 d as described herein. While the conductor 90 includes two filars 92 a and 92 b, the conductor 90 may alternatively include more than two filars.

The insulative layer 94 a is removed from the filar 92 a along a portion of the conductor 90 to provide an electrode 96. In order to increase the surface area of the conductive portions of the electrode 96, the conductor 90 further includes additional uninsulated filars 98 a, 98 b, 98 c, 98 d wound adjacent to the uninsulated portion of the filar 92 a. The filars 98 a-98 d are not connected to the connector 20 at the proximal end 17 of the lead 14, and thus do not receive electrical signals directly from the control module 12. Rather, the filars 98 a-98 d conduct the electrical signals received by the filar 92 a from the control module 12. In some embodiments, the terminal ends of the filars 98 a-98 d are at or near the proximal and distal ends of the electrode 96. The filars 98 a-98 d may be comprised of a conductive material similar to filars 42 a-42 d as discussed herein. In some embodiments, the filars 98 a-98 d are electrically and mechanically coupled to the uncoated filar 92 a via laser welding. While four additional filars 98 a-98 d are shown, the conductor 90 may include any number of filars 98 to increase the surface area of the electrode 96. Similar assemblies of additional filars adjacent to uninsulated portions of filars 92 may be formed at other longitudinally spaced sections of the lead 14 to define additional electrodes. While electrode 96 is illustrated as extending co-radially with the insulated portions of the filars 92 a and 92 b, in some embodiments, the electrode 96 is disposed at the outer surface of the conductor 90 to form a substantially constant outer diameter. That is, in some embodiments, the outer diameter of the insulated filars 92 a, 92 b is approximately equal to the outer diameter of the electrode 96. In still further embodiments, the outer diameter of the electrode 96 is greater than the outer diameter of the insulated filars 92 a, 92 b.

FIG. 6 is a cross-sectional view of a temporary lead coil conductor 100 according to another embodiment of the present disclosure. In the illustrated embodiment, the conductor 100 is a bifilar conductor including filars 102 a and 102 b coated by insulative layers 104 a and 104 b, respectively. The filars 102 a and 102 b may be comprised of a conductive material such as those discussed herein with respect to filars 42 a-42 d. The insulative layers 104 a and 104 b may be comprised of an insulative material such as those discussed herein with respect to insulative layers 44 a-44 d. In addition, the dimensions of the filars 102 a and 102 b and insulative layers 104 a and 104 b may be similar to the dimensions of filars 42 a-42 d and insulative layers 44 a-44 d as described herein. While the conductor 100 includes two filars 102 a and 102 b, the conductor 100 may alternatively include more than two filars.

The conductor 100 is a variation on the conductor 90 illustrated in FIG. 5, wherein instead of additional filars employed to increase the surface area of the electrode, the electrode 106 in the conductor 100 includes a conductive ribbon 108 to increase the electrode surface area. That is, the insulative layer 104 a is removed from the filar 102 a along a portion of the conductor 100. The conductive ribbon 108 is wound adjacent to the uninsulated portion of the filar 102 a. The conductive ribbon 108 is not connected to the connector 20 at the proximal end 17 of the lead 14, and thus does not receive electrical signals directly from the control module 12. Rather, the conductive ribbon 108 conducts the electrical signals received by the filar 102 a from the control module 12. In some embodiments, the conductive ribbon 108 is welded to the uninsulated portions of the filar 102 a. The conductive ribbon 108 may be comprised of a conductive material similar to filars 42 a-42 d as discussed herein. While electrode 106 is illustrated as extending co-radially with the insulated portions of the filars 102 a and 102 b, in some embodiments, the electrode 106 is disposed at the outer surface of the conductor 100 to form a substantially constant outer diameter. That is, in some embodiments, the outer diameter of the insulated filars 102 a, 102 b is approximately equal to the outer diameter of the electrode 106. In still further embodiments, the outer diameter of the electrode 106 is greater than the outer diameter of the insulated filars 102 a, 102 b.

FIG. 7 is a cross-sectional view of a temporary lead coil conductor 110 according to another embodiment of the present invention. In the illustrated embodiment, the conductor 110 is a bifilar conductor including filars 112 a and 112 b coated by insulative layers 114 a and 114 b, respectively. The filars 112 a and 112 b may be comprised of a conductive material such as those discussed herein with respect to filars 42 a-42 d. The insulative layers 114 a and 114 b may be comprised of an insulative material such as those discussed herein with respect to insulative layers 44 a-44 d. In addition, the dimensions of the filars 112 a and 112 b and insulative layers 114 a and 114 b may be similar to the dimensions of filars 42 a-42 d and insulative layers 44 a-44 d as described herein. While the conductor 110 includes two filars 112 a and 112 b, the conductor 110 may alternatively include more than two filars.

The filars 112 a and 112 b of the conductor 110 are wound in alternating multi-turn segments. In the embodiment shown, the filars 112 a, 112 b are wound in alternating four turn segments. To achieve this configuration, the filar 112 a is wound with a plurality of adjacent turns, and then a connecting portion 116 a extends within the lumen 118 formed by turns of the filar 112 b to the next multi-turn segment of the filar 112 a. Likewise, the filar 112 b is wound with a plurality of adjacent turns, and then a connecting portion 116 b extends within the lumen 118 formed by turns of the filar 112 a to the next multi-turn segment of the filar 112 b.

To form electrodes, the insulative layer 114 a, 114 b is removed from one or more multi-turn segments of the filars 112 a, 112 b. For example, in the embodiment illustrated in FIG. 7, the insulative layer 114 a is removed from a multi-turn segment of the filar 112 a to form a proximal electrode 126, and the insulative layer 114 b is removed from a multi-turn segment of the filar 112 b to form a distal electrode 128. In some embodiments, the uninsulated multi-turn segment of the filar 112 a forming the electrode 126 are welded together, and/or the uninsulated multi-turn segment of the filar 112 b forming the electrode 128 are welded together. The welding forms an electrode surface at an exterior of the lead 14.

Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof. 

We claim:
 1. A temporary implantable medical device lead comprising: a connector configured to connect the lead to an external control module; and a helically coiled conductor having a proximal end mechanically and electrically connected to the connector, the conductor including a plurality of insulated filars, wherein an insulative layer is removed from an uninsulated portion of each of the filars near a distal end of the conductor, and wherein the uninsulated portion of each of the filars is exposed at an outer surface of the conductor such that the exposed uninsulated portions of the filars define a plurality of electrodes at longitudinally spaced sections near the distal end of the conductor.
 2. The temporary implantable medical device lead of claim 1, wherein a first electrode is defined by the uninsulated portion of at least one of the plurality of filars and a second electrode is defined by the uninsulated portions of at least one other of the plurality of filars.
 3. The temporary implantable medical device lead of claim 1, and further comprising: a conductive mechanical element including one or more grooves that electrically couple with the uninsulated portion of at least one filar.
 4. The temporary implantable medical device lead of claim 3, wherein one or more grooves have a depth approximately equal to a diameter of the retained at least one filar.
 5. The temporary implantable medical device lead of claim 1, and further comprising: one or more conductive elements wound co-radially with and electrically coupled to the uninsulated portion of at least one filar of the conductor, wherein the one or more conductive elements are not mechanically connected to the connector at the proximal end.
 6. The temporary implantable medical device lead of claim 5, wherein the one or more conductive elements comprises one or more additional filars.
 7. The temporary implantable medical device lead of claim 5, wherein the one or more conductive elements comprises a ribbon conductor.
 8. The temporary implantable medical device lead of claim 1, wherein the plurality of filars are wound in alternating multi-turn segments, and wherein one or more multi-turn segments for each filar are exposed at the outer surface of the conductor to define the plurality of electrodes.
 9. A system comprising: an externally carried control module; and a temporary implantable medical device lead including: a connector configured to connect the lead to the control module; and a helically coiled conductor having a proximal end mechanically and electrically connected to the connector, the conductor including a plurality of insulated filars, wherein an insulative layer is removed from an uninsulated portion of each of the filars near a distal end of the conductor, and wherein the uninsulated portion of each of the filars is exposed at an outer surface of the conductor such that the exposed uninsulated portions of the filars define a plurality of electrodes at longitudinally spaced sections near the distal end of the conductor, wherein, during stimulation, the control module is configured to operate a first of the plurality of electrodes as a cathode and a second of the plurality of electrodes as an anode.
 10. The system of claim 9, wherein a first electrode is defined by the uninsulated portion of at least one of the plurality of filars and a second electrode is defined by the uninsulated portions of at least one other of the plurality of filars.
 11. The system of claim 9, and further comprising: a conductive mechanical element including one or more grooves that electrically couple with the uninsulated portion of at least one filar.
 12. The system of claim 11, wherein one or more grooves have a depth approximately equal to a diameter of the retained at least one filar.
 13. The system of claim 9, and further comprising: one or more conductive elements wound co-radially with and electrically coupled to the uninsulated portion of at least one filar of the conductor, wherein the one or more conductive elements are not mechanically connected to the connector at the proximal end.
 14. The system of claim 13, wherein the one or more conductive elements comprises one or more additional filars.
 15. The system of claim 13, wherein the one or more conductive elements comprises a ribbon conductor.
 16. The system of claim 9, wherein the plurality of filars are wound in alternating multi-turn segments, and wherein one or more multi-turn segments for each filar are exposed at the outer surface of the conductor to define the plurality of electrodes.
 17. A temporary implantable medical device lead comprising: a connector configured to connect the lead to an externally carried control module; and a lead body including a helically coiled conductor, a proximal end of the conductor mechanically and electrically connected to the connector at a proximal end of the lead body, the conductor including a plurality of insulated filars, wherein an insulative layer is removed from an uninsulated portion of each of the filars near a distal end of the conductor, and wherein the uninsulated portion of each of the filars is exposed at an exterior of the lead body such that the exposed uninsulated portions of the filars define a plurality of electrodes at longitudinally spaced sections.
 18. The temporary implantable medical device lead of claim 17, wherein a first electrode is defined by the uninsulated portion of at least one of the plurality of filars and a second electrode is defined by the uninsulated portions of at least one other of the plurality of filars.
 19. The temporary implantable medical device lead of claim 17, and further comprising: a conductive mechanical element including one or more grooves that electrically couple with the uninsulated portion of at least one filar.
 20. The temporary implantable medical device lead of claim 19, wherein the one or more grooves have a depth approximately equal to a diameter of the retained at least one filar. 